Activation, decay heat, and waste disposal analyses for the ARIES-AT powerplant

Detailed activation, decay heat and waste disposal calculations of the ARIE S-AT design are performed to evaluate the safety aspects of the device. The high initial activity of the SiC highly irradiated components translates d irectly into a higher initial decay heat for these structures than for the well-protected steel-based components. However, after a one-hour cool-down period, the SiC decay heat drops by two decades to levels comparable to the steel-based components. The decay heat of the LiPb coolant was found to ex ceed that of the SiC components for several days after shutdown. This impli es that a loss of flow accident (LOFA) event is more critical than a loss o f coolant accident (LOCA) event for LiPb/SiC systems. Regarding waste dispo sal, all structures can easily meet the Class C Low-Level Waste (LLW) requi rements established for the ARIES power plants. Many components could quali fy as Class A LLW after a 100-year storage period after selection of low ac tivation materials and control of the Nb and Mo impurities in ferritic stee l. A purification system will be required to remove the Po-210 and Hg-203 g enerated by Pb during operation.